1. Field of the Invention
The present invention relates to a support device for a preparation, in particular a biological preparation, which is suitable for isolating individual objects, in particular biological objects such as cells or chromosomes, contained in the preparation from the preparation by means of laser irradiation, and for thereby separating them from the preparation.
2. Description of Related Art
Generic support devices are used, for example in the field of microdissection, for sorting and harvesting individual biological cells. A corresponding process is described, for example, in WO 97/29355 A of the Applicant. This document describes how a selected biological object is separated from the surrounding biological mass located on a planar support, so that the selected biological object is prepared in isolation from the surrounding biological mass. For this purpose the selected biological object is cut out of the surrounding biological mass by means of laser irradiation. The biological object isolated in this way is then catapulted from the support to a collecting device by means of a laser shot, in which case the collecting device can be, for example, a collecting substrate or a collecting “cap”. This method is generally used in combination with a suitable microscope arrangement to control the cutting and catapulting process in a microscope-supported manner. The laser beam for cutting out and/or catapulting a selected biological object can be controlled in a computerised manner. To harvest, i.e. separate, a single biological object it is not absolutely necessary to first carry out a cutting process and then a catapulting process by means of two separate laser irradiations; investigations have shown that, depending on the laser energy and the laser focus and on the constitution of the biological material to be treated, a single laser shot can be sufficient to separate the desired biological object directly from the surrounding biological mass and to catapult it into the collecting device.
The preparation to be processed with the laser irradiation is generally located on a glass object carrier. It can, however, also be located on a carrier membrane absorbent to the laser light used, which carrier membrane is cut together with the preparation in the course of the cutting process. In the subsequent catapulting process the isolated biological object together with the corresponding severed portion of membrane is catapulted into the collecting device. The use of such a carrier membrane is advantageous since relatively large objects can thereby be catapulted out completely using single laser shots, the carrier membrane acting as a tray with which relatively large areas can be transported and catapulted. Smaller biological objects such as filaments or chromosomes can be more easily isolated because they adhere to the carrier membrane and can then be catapulted morphologically intact into the collecting device together with the corresponding membrane portion in the catapulting process.
The handling of such a carrier membrane is, however, extremely problematic since this membrane is very thin, having a thickness in the range of micrometers. Together with the carrier membrane which serves to receive the preparation to be worked, a carrier transparent to laser light must therefore be used to carry or support the membrane. A glass object carrier of the kind used in known microscopes or the like is conventionally used for this purpose. The membrane is generally applied to the glass object carrier manually, i.e. the membrane is placed by the user on the glass object carrier and optionally fixed to the glass object carrier by the application of a special adhesive between the membrane and the glass object carrier.
This procedure is, however, relatively complex. Furthermore, because of the “waviness” of the membrane, individual gaps, which impede the laser treatment and the observation by microscope usually carried out concurrently, cannot be prevented from forming between the membrane and the object carrier. Such gaps also occur when applying an adhesive for bonding the membrane to the object carrier, since aqueous solutions or aqueous preparations (e.g. alcohol) are frequently used, in particular, in the field of biological, chemical or medical analyses or experiments, so that contact between the adhesive and water cannot be precluded, which has the undesired consequence when using a water-soluble adhesive that the membrane becomes detached from the object carrier.